Fish

Plants

Bacteria

What is Aquaponics?

Aquaponics is the method of growing fish and vegetables together in a 'closed-loop' recirculating system

Aquaponics systems have three main components - Fish, Plants and Bacteria. The bacteria are a commonly overlooked part of an aquaponic system but it is these that do the most important work in the nutrient cycle. Aquaponics usually uses no soil at all - but it can use either an alternative growing media such as clay pebbles, pumice stone, lava rock or gravel, or the plants can simply be grown in the nutrient rich waters coming from the fish tanks.

Why Aquaponics?

• The best tasting home-grown vegetables!

• Great tasting, Organic food grown in your own system

• No unnatural Herbicides, Pesticides or Fertilisers

• Exceptionally water efficient - 5% of normal usage

• Higher growth rates and yields

• Can be easily used in small, urban areas.

• Healthy, clean, home-grown fish for you

• No genetic manipulation of the fish

• Fish are a healthy source of protein

• Water quality is high, so the taste is high

• Water recirculation reduces pollution

• Local production reduces "food miles"

Fish and vegetables have been proven to be one of the healthiest diets

The Aquaponics Cycle

4

Plants use the nitrates and other minerals now readily available in the system as natural fertiliser! Clean water now returns to the fish tank and the nitrogen cycle continues.

1

3

Fish produce ammonia, NH3, from their gills and solid waste from their excretions. Solid waste breaks down into AMMONIA (NH3), and mineral nutrients. Total ammonium is NH4

Fortunately, Nitrospira or Nitrabacter bacteria will quickly break down these nitrites into far more plant-friendly NITRATES (NO3)

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Nitrosomonas bacteria break down the ammonia into even more poisonous NITRITES (NO2)!!

The

NITROGEN

CYCLE

Oxygen is vital to every organism in an aquaponics system - design your system with lots of passive aeration such as splashing by-pass valves and venturi's. Aeration pumps can also be used.

For a healthy system you must circulate at least 100% of the fish tank water at least once every hour, but as much as 2 or 3 times every hour if you have the right type of fish and system setup.

Fish capacity should be linked to the mechanical, biological and bacterial filtration capacity of your system - overstocking fish will lead to fish deaths and the breakdown of your system.

Bacteria like a warm, well oxygenated environment so you should keep the temperature up. Approximately 25-35° C is ideal for them as this is the range in which they are biologically most active.

Types of Aquaponic Systems

There are several different types of aquaponic systems that have developed over the past 30 years or so, and each can be used in different ways depending on your situation. A commercial system will be very different from a home or backyard system - but nevertheless, there are several common components and 3 widely accepted and used systems.

Home Systems

Small Commercial

Hybrid Systems

Media Filled Growbeds

These are the simplest form of aquaponics. They use containers filled with a suitable growing media such as expanded clay balls, pumice stone, gravel or something similar. Water from a fish tank is pumped over the media filled beds and plants grow in the rock media.

This style of system can be run two different ways, with a continuous flow of water over the rocks, or by flooding and draining the grow bed in a 'flood and drain' or 'ebb and flow' cycle.

The growbeds should be about 12" in depth as this has been proven to be the most effective depth for plant growth and the cultivation of a beneficial ecosystem in the beds.

Once the water reaches the appropriate level then it will be drained from the growbed (usually quickly) which will draw oxygen back down into the growbed for the benefit of the plants and microbes. This cycle then continues regularly and provides the plants with all of the nutrients that they need to grow extremely abundantly and naturally without any added pesticides, herbicides or fertilisers.

Small Commercial

Hydroponic Conversions

Hybrid Systems

Nutrient Film Technique

This is a commonly used hydroponic method, but is not as common in aquaponic systems. In NFT systems, nutrient rich water is pumped down small enclosed gutters, the water flowing down the gutter is only a very thin film. Plants sit in small plastic cups allowing their roots to access the water and absorb the nutrients.

NFT is only really suitable for certain types of plants such as leafy greens and herbs because larger plants will have root systems that are too big and invasive, or they become too heavy for the lightweight growing gutters.

NFT is more commonly used in commercial aquaponic systems but can be successfully used in a hobby system provided that the water is filtered before it is used in the NFT channels.

Unfiltered water from the fish tanks will contain many particulates which will attach to the plant roots and will ultimately stop their ability to take up nutrients and oxygen.

aquaponics DWC deep water culture system

Commercial Systems

Hybrid Systems

Deep Water Culture

This method works on the idea of floating plants on top of the water allowing the roots to hang down into the nutrient-rich water. This can be done in a number of ways and this method is one of the more commonly practised commercial methods.

DWC can be done by floating a foam raft on top of the fish tank, however a more common method is to grow the fish in a fish tank and pump the water through a filtration system and then into long channels where floating rafts filled with plants float on the water surface and extract the nutrients.

The water must be filtered before it reaches the channels as particulates and solids in the water will clog up the root systems of the plants and will inhibit their ability to take up oxygen and nutrients.

DWC is the most commonly used method in commercial aquaponic systems as it provides the versatility to grow a relatively wide variety of leafy plants and herbs and can be set up relatively inexpensively.